The invention relates to an arrangement for employing a drill steel centralizer travelling on a feed beam of a rock drill machine, the arrangement comprising a feed cylinder for moving the drill machine in the drilling direction and back, at least one turning wheel mounted stationary in relation to the feed cylinder and a flexible feed member running around it and connected both to the drill machine and the feed beam, a drill steel centralizer mounted to travel on the feed beam and stationary in relation to the feed cylinder in the longitudinal direction of the feed beam and having a central opening for a drill rod, a transfer opening at the side of the central opening for transferring the drill rod to the central opening and away from it and means for closing the transfer opening during drilling, and pressure fluid channels for feeding pressure fluid in to and out of the pressure fluid chambers of the feed cylinder.
When using long drill rods, and especially in long hole drilling, a drill steel centralizer travelling on the feed beam is generally used to support the drill rods; the centralizer being located between the drill machine and the drill steel guide at the front end of the feed beam and travelling on the feed beam as the drill machine moves. To produce the feed and return movement of the drill machine, very often a feed cylinder is used that is connected to move a wire or chain connected to the drill machine carriage. A change in the length of the feed cylinder then produces the movement of the drill machine. In known structures the longitudinal movement of the feed beam produces a movement of twice the length for the drill machine with the same ratio for the rates of travel. Typically the centralizer in connected to move with the moving part of the feed cylinder, i.e. the cylinder tube or piston depending on the used solution. Generally the piston rod of the feed cylinder is at its end connected stationary in relation to the feed beam, and the cylinder tube moves to produce the feed movement.
In general a centralizer is used that has an opening at the location at which the drill rod is brought to the drill machine. A problem with this solution is that the drill rod at times slips away from the centralizer, which means that drilling must be stopped and the drill rod wrenched back to the centralizer.